[Dune] Parallel dune-uggrid

[Christian Engwer]

Hi Rene,

yes, there is a very short answer.

UG uses an internal abstraction for parallel communication (MPI is
only one option out of many, and actually it does much more than just
message passing) called DDD. This DDD library uses global state and
thus can't handle multiple meshes.

It would be possible to change this and use individual instances
instead of global state, but this requires _very_ much work, as one
has to touch every place where DDD is used.

Best
Christian

On Wed, Mar 01, 2017 at 12:03:21PM +0100, René Milk wrote:
> Hi all,
> 
> from comments in dune-grid [1] I get that uggrid is limited to a single grid
> instance when compiled for parallel computations. Is this still the case with
> the current version? If it is, is there a short/simple explanation of why this
> limitation exists?
> 
> Thanks,
> René
> 
> [1] dune/grid/utility/test/structuredgridfactorytest.cc